In printing machines and especially sheet-fed offset printing machines, safety regulations often require the printing machine to emit an acoustic alarm signal before the start-up of the printing machine. After the operator of the printing machine enters the specific start-up command (such as inching, creep speed, speeding up to basic or production rotational speed, etc.) via a command button, the printing machine sounds an alarm tone for a specified period of time (e.g. three seconds). After the emission of this alarm tone, the operator must re-enter the specific start-up command within a specified period of time (e.g. ten seconds). Only after the operator enters the two commands in sequence does the control unit of the printing machine start-up the drive. An acoustic start-up alarm device for printing and paper processing machines is described in DIN 8738, November 1990.
In the prior art, start-up alarm devices could possibly fail to emit the alarm signal prior to the start-up of the printing machine. Defects in the signal transmitters or in the drive electronics connected upstream to the start-up alarm device could cause the start-up alarm device to malfunction. This represents a danger to personnel in that those in proximity to the printing machine have no audio warning prior to start-up of the printing. In particular, certain printing machine operations, such as an inching operation which drive the machine with open guards, necessitate the sounding of an alarm before the start of operation.